1. Field
Methods and apparatuses consistent with exemplary embodiments relate to a calibration method which is executable by using a photon counting X-ray detector.
2. Description of the Related Art
A photon counting X-ray detector may separate X-rays which are applied to the photon counting X-ray detector, for each photon energy band.
Because a conventional integration type detector adds all electrical signals generated by an X-ray photon which are applied to the conventional integration type detector, regardless of photon energy, it may be difficult to separate photon energy.
In a conventional method used for energy calibration of a photon counting detector, a spectrum of an X-ray which is measured by using a photon counting X-ray detector is used.
In the conventional method, an X-ray spectrum may be obtained by obtaining an image while changing a threshold energy value at equal intervals and by calculating a signal difference caused by a change in threshold energy.
In an example, an energy calibration scheme using a spectrum of an X-ray may be performed by setting an X-ray tube at a predetermined acceleration voltage peak kilovoltage (kVp), by measuring an X-ray spectrum using a photon counting X-ray detector while irradiating an X-ray, and by mapping a location in which the spectrum has a value of “0” to the predetermined acceleration voltage.
However, in this example, because it is difficult to accurately measure the location, the accuracy of the mapping may be reduced.
In another example, an energy calibration scheme may be performed by imaging a material having an absorption edge in a used X-ray energy area, and by mapping a location of an absorption edge measured in an acquired spectrum to energy of an absorption edge of an actual material.
However, in this example, the uniformity of a value which is measured by using a photon counting X-ray detector may be reduced due to a limitation on a location measurement accuracy of an absorption edge.
In still another example, an energy calibration scheme may be performed by obtaining a spectrum while measuring an X-ray which is generated in a radioactive isotope, and by mapping a predetermined energy of an isotope to a peak of the spectrum.
However, in this example, the energy calibration scheme requires an additional instrument which is used to manage a high radioactive isotope.